Aecom Technology Corp. announced two acquisitions this week with a combined price tag of $679 million.

The Los Angeles engineering services company purchased McNeil Technologies, a government defense and intelligence contractor based in Springfield, Va., for $355 million. Davis Langdon, a cost and project management firm headquartered in London, U.K., was acquired for $324 million.

McNeil has about 1,500 employees and generated $245 million in revenue in 2009. Davis Langdon has about 2,500 workers and reported revenue of $430 million.

“We are pleased to be in a position to put our balance sheet to work to fund strategic acquisitions in today’s highly attractive mergers and acquisitions market,” said Aecom Chief Financial Officer Michael Burke in a statement.

Aecom, a Fortune 500 company, is one of the largest engineering services company in the world, with 45,000 employees and 2009 revenue of $6.1 billion.

Shares of Aecom closed Friday at $25.37, up 15 cents, or 1 percent, since the first acquisition was announced on Wednesday.